The objective of this proposal is to investigate whether the capsule of the salivary gland plays a role in regulating the repair process following the removal of a portion of parenchyma from the submandibular or parotid glands. Present knowledge of capsular physiology is scant. Normally, this outer covering is underlain by the glandular tissue comprising the bulk of the salivary gland and consisting primarily of the acini and ducts. If some of this tissue is excised, scarring might eventually be expected to occur at the site. Preliminary data obtained in the rat and the dog, however, indicate that such is not the case; it is possible to obtain paranchymal repair in the salivary glands of adults of both species. Moreover, as a result of varying the relationship between the capsule and the residual salivary tissue, the amount of restitution that occurs can vary from insignificant to appreciable. Thus, the capsule seems able to determine, at least in part, the extent to which the innate tendency of the salivary parenchyma to repair itself will be permitted to become manifest. This regulatory ability would seem to be a potential function of the salivary gland capsule which can become activated when there is a need for repair to occur. Serial studies employing routine histologic procedures and autoradiography using tritiated thymidine will permit following the sequential changes occurring during the healing process under several experimental conditions which will modify the capsular topography.